Reciprocating agitator



R. M. GOLD RECIPROCATING AGITATOR March 19, 1963 United States Patent O 3,081,746 RECEPRCATENG AGITATR Robert M. Gold, Minneapolis, Minn., assigner to Dayton Rogers Manufacturing Co., Minueapoiis, Minn., a corporation or Minnesota Fiied Feb. 1i), 1961, Ser. No. 83,327 9 Claims. (Cl. 121-164) This invention relates to a reciprocating agitator, and more particularly relates to a pneumatically operated reciprocating agitator.

An object of my invention is to provide a pneumatic reciprocating agitator of simple and inexpensive construction and operation.

Another object of my invention is the provision of a novel reciprocating agitator wherein the length of the reciprocating stroke may be readily and easily varied over a wide range.

Still another object of my invention is to provide an improved pneumatic reciprocating agitator adapted to operate at various speeds at diierent portions of the operating cycle.

A further object of my invention is the provision of a novel and improved pneumatic reciprocating agitator wherein the operating speed at various individual portions of the operating cycle may be readily and easily varied.

A still further object of my invention is to provide a new and novel pneumatic reciprocating agitator with simple and inexpensive controls for starting and stopping the operation thereof.

A still further object of my invention is to provide a novel reciprocating agitator which may be employed for a wide variety of uses and which is readily portable and simply put into operation by merely connecting to an air supply, and which is further variable in all respects for controlling the reciprocating motion.

These and other objects and advantages of my invention wili more fully appear in connection with the following description made in connection with the accompanying drawings wherein like reference characters refer to the same parts throughout the several views and in which:

FIG. l is a perspective view of the invention shown in a typical use;

FIG. 2 is an elevation view of the apparatus with portions of the housing and frame broken away from clarity of detail;

FIG. 3 is a view taken at 3-3 in FIG. 2 with portions of the apparatus being shown in sect-ion for clarity of detail and also having portions of the frame broken away;

FIG. 4 is a detail section view taken at 4-4 in FiG. 3

FG. 5 is an enlarged detail section view taken approximately at 5 5 in FIG. 3; and

FiG. 6 is a detail view showing a modified form of the work-engaging media at the end of the piston rod.

FIG. 7 is a schematic sketch of the control valve and showing portions of the various pipes and conduits connected thereto.

One form of the present invention is shown in FIGS. 1-5 and is described in detail herein.

The reciprocating agitator is indicated in general by numeral 1t), and as seen in FG. l, the agitator may be supported by any suitable medium such as a chain hook 11, and may support a workpiece or work-holding apparatus such as basket 12 in which cast parts may be tumbled around and possibly jiggled in a liquid bath.

The agitator 1d includes a frame 13 which includes an elongate rigid mounting plate 14 having transversely extending end portions 14a and 14h, between which are provided a pair of angle bars 15.

A pneumatic cylinder .-16 is affixed as by screws 17 lends of the cylinder.

3,681,746 Patented Maru 19, 1963 FCice to the end 14a of the frame plate, and by screws 18 to a bracket 19 which is aixed as -by welding to the frame plate 14. The air cylinder 16 has a piston rod 20 and an internal piston 21, and air ports Z2 and 23 at the opposite The piston rod 2t) has an outer end portion 24 which is connected to the rod 20 at the bifurcated portion 29a thereof by a pin 25 which projects slightly outwardly at one side in the manner shown. The outer terminal end of the vouter portion 24a of the piston rod constitutes a work-engaging media and in the form shown comprises a hook 26 for supporting the basket or other device 12 as seen in FIG. l. As seen in FIG. 6, the outer terminal portion 26 might take a slightly different form to accommodate a pair of bolts 26a so that a ditferent type of workpiece such as 12' might be employed to produce a pushing action on the piece `12 instead of merely a lifting action.

It will be noted that the outer portion 24 of the piston rod has an elongated slot 24a therein. A housing 27 encompasses the frame, pneumatic cylinder 16 and piston rod, and at one side thereof is provided with an elongated slot 2S to accommodate an outwardly projecting handle 29 which is threadedly connected at 30 to a stem portion 31 of an abutment 32 on the rod portion 24 and is adapted to be tightened against the rods so that the abutment is immobile with respect to the piston rod, or may be adjusted along the length thereof.

The air ports 22 and 23 of cylinder 16 are respectively connected by air conduits 33 and 34 to a two-position four-way air valve 35 by the ittings 33a and 34a respectively. The valve 35 is also connected to an air supply pipe 36 which is to be connected to a source of air under pressure. The valve 35 is also provided with exhaust port 37 from which air is exhausted into the atmosphere through iitting 38.

The valve 35 is provided with an elongate, longitudinally shiftable operating stem 39, the opposite ends of which extend longitudinally outwardly of the opposite ends of the valve 35. The valve 35 is of typical two-position four-Way construction whereby the fitting 33a and 34a and the corresponding parts on the valve are individually and Kalternately connected in tluid communication with the air supply pipe 36 and the exhaust port 37 in the two longitudinal positions of the operating stem 39. More specifically, the air conduit 33 is connected to the air supply pipe Iand to the `source of air under pressure when the valve stern 39 is shifted longitudinally toward the pneumatic cylinder 16 or toward 4arrow a, and the conduit 34 is simultaneously connected with the exhaust port 37. When the valve stem 39 is shifted longitudinally away from the cylinder 16, the air conduit 34 is connected to the air sup-ply pipe 36 and to the source of air under pressure, and the air conduit 33 is simultaneously connected to the exhaust port 37. j

The valve 35 is operated when the piston rod 2t) and its forward portion 24 are in predetermined position so as to reverse the air connections to the cylinder 16 and thereby reverse the direction of movement of the piston rod.

`To operate the valve 35, a pair of stem-pushing elements `40 and 41 are disposed with their inner portions adjacent the opposite ends of the valve stem 39. The inner portions of elements 40 and 41 are interconnected by a tension spring 42 which continuously urges each of the stempushing elements toward the stern 39. The outer end portion of element 40 is swingably mounted on a pivot 43, which is carried by a suitable bracket 44 aixed, as by Welding to the frame plate 14, and the inner portion of the element 40 is adapted to swing in a direction longitudinally of the valve stem 39. The stem-pushing element 41 is mounted on a slide rod 45 which extends through and is slidably related in suitably provided bearing apertures in bracket elements 46 and 47 which are aixed to the frame plate 14 as by welding.

The outer portion of the stem-pushing element 40 is provided with ya projection 48 which is disposed adjacent the end 45a of the slide rod 45 so as to cooperate therewith in forming a latching mechanism to move the stem-pushing elements 40 and 41 in predetermined desired positions. The projection 48 has one side 49 adapted to be swung into juxtaposition and generally parallel relation with the end portion of the slide rod 45, and the projection 48 also has an abutting end portion Stil which may be swung into endwise abuttin-g relation with the end y45a of the slide rod.

The operating stem 39 of the valve 35 is provided with an elongate extension bar 51 which extends through and is slidably related in an aperutre 41a in the stem-pushing element 41. A movable stop bar 52 is iswingably mounted by a rivet 53 on the frame plate 14 so as to be adapted to'be swung into and out of confronting relation with the end of an extension bar 51, and the stopl bar 52 is aixed as by welding to a handle 54 which projects to the exterior of the housing 27. A tension spring 55 is connected at one end to the stop bar 52 and at the other end to the bracket plate 19 and is positioned with respect to the pivoting rivet '53 so that the tension spring 55 swings over center of swinging stop bar 52 and holds the stop bar either in confronting relation or out of confronting relation with the stem extension rod S1. The effect of the stop bar 52 is to prevent longitudinal movement of the valve-operating ystem 39, which thereby prevents change of the air connections to the air cylinder and operation of the cylinder and piston therein will stop.

In each of the air conduits 33 and 34 is provided an air ow regulating valve 56 which is shown in detail in FIG. and permits unrestricted ow of air into the cylinder, and regulates the rate of flow of air out of the cylinder whereby to control the speed of movement of the piston and piston rod in the respective directions. In the form shown, each of the valves 56 includes a hollow valve body 57 internally threaded at its opposite ends to receive the fittings of air conduit 34. The valve body 57 has a central ow channel 58 and a valve seat 59 against which is normally pressed a ball 60 by means of a spring 61 to define a check valve. The spring 61 is anchored by `a ball stop bracket 62, having out-turned ends anchored in a `suitably provided groove in the interior wall of the valve body. The bracket 62 is generally strap-like in configuration and therefore it does not obstruct the ow of air in the interior of the valve body 57. The valve bodyvalso includes continuously open ports 63 and 64, between which is defined an exterior rounded shoulder portion 65, which delines, together with the interior surface 66 of the regulating sleeve 67, a flow restriction which may be varied, depending upon the longitudinal position of the sleeve 67. It will be seen that the sleeve A67 is threadably mounted Iat 68 to the exterior, of the valve `body 57, and is sealed thereto by gasket rings 69, and is normally prevented from being removed by a spring retaining ring 70.

A suitable lfitting 71 is provided on the end 14a of frame plate 14 to provide for mounting of the lagitator in a desired manner. Of course the fitting 71 could take other various forms as compared to the simple loop that is shown.

In the operation of the agitator, air pressure is applied in the air supply pipe 36 and, depending upon the position of the valve .35, air under pressure is supplied to one or the other of the ends of the cylinder 16, and simultaneously the opposite end of the cylinder is opened to the atmosphere. In the position of the apparatus shown in the drawings, the agitator is in non-operating condition because the stop bar 52 has been swung into confronting and engaging relation with the stem extension 51 so as to prevent operation of the valve, and in this situation, air under presure is supplied at the pipe 36, provided through conduit 34 and through cylinder port 23 and the other end of the cylinder is open to atmosphere.

lf the handle 54 is swung upwardly, as seen in FG. 2, the valve stem is free to move and will be immediately moved by operation of spring d2 and element 40 to a shifted position, whereupon the air connections in the valve 35 are reversed, and the abutting end surface Si) of the projection 48 is swung into confronting relation with the end 45a of the slide bar 45, thus preventing any material endwise movement of the stem-pushing element 41. When theV valve 35 has reversed its air connections, air under pressure is supplied through conduit 33 and cylinder port 22 to move the piston rod outwardly of the cylinder. Simultaneously, air is being exhausted from the cylinder port 23 and through the air conduit 34 to the exhaust port 37 of the valve and this exhausting of air is controlled, as for velocity, by the operation of the regulating valve 56 so that the desired speed of piston movement is obtained. If it were desirable to reduce the rate of piston movement, the sleeve 67 would be turned with respect to valve body 57 so as to reduce the space between the surfaces 65 and 6601": the valve body and the sleeve respectively, and conversely if it were desired to increase the speed of movement of the piston, the sleeve would be oppositely moved to increase the space between surfaces 65 and 66 of the valve body and sleeve respectively.

As the piston rod moves progressively outwardly, the pin 2-5 moves away from the stem-pushing element 41, and then the abutment 32 progressively moves toward the stem-pushing element 40. When the abutment 32 en gages t-he inner portion of stem-pushing element 4), the element 40 is swung so as to move the projection 43 and thereby swing the abutment surface 5t) thereof out of confronting relation with the end 45a of the slide bar 45, thus allowing longitudinal movement of the slide bar 45 and stem-pushing element 41 under the influence of tension spring 42, whereupon, the stem-pushing element 41 engages the end of the valve-operating stem 39 and longitudinally moves the same back to the full line position shown in the drawings, and of course, this reverses the `air connections in valve 35 so as to again reverse the air connections in the cylinder 16. Air under pressure is' applied through port 23 and the air is exhausted through the port 22 and through air conduit 33. It should be noted that the regulating valve 56 in the conduit 33 may have a different setting than the regulating valve in the lair conduit 34. By various adjustments of these regulating valves the agitator may be adjusted to have a quick projection of the piston rod and a slow return, or conversely may be adjusted to have a slow projection and quick return, or, similarly, the rod may be moved either slowly or quickly on both the projection yand return.

As the piston rod is being returned into the cylinder, the side 49 of the projection 48 will lie along the side of the slide bar 45 so as to prevent the stem-pushing element 40 from swinging longitudinally toward the valve stem 39 and the valve stem will remain in stationary position. As the piston rod is returning, the pin 25 engages the stempushing element 41 and moves the same away from the end of the operating stem 39 and increases the tension on spring 42, and as the element 41 is being moved, the end 45a of the slide bar will move past the end of the projection 48, whereupon the projection 48 and sternpu-shing element 46 is free to swing. The tension on spring 42 will swing the element 4@ against the end of operating stem 39 so as to move the stem and operate the valve to change the air connections therein.

As soon as the air connections in the valve are changed, the air pressure in the cylinder 16 causes reversal of direction of movement of the piston rod and immediately the cycle as described starts over again.

Of course if it is desired to stop the operation of the agitator, the lever d4 is swung downwardly as shown and when the valve stem subsequently attempts to move under the influence of element d0 and spring 42, the

movement of the valve stem 39 is prevented by the stop bar S?. and operation of the cylinder 16 is prevented.

The length of stroke of the piston rod may be readily and easily varied by loosening the handle 29 and abutment 32 and sliding the abutment to a new position along the length of the outer portion 24 of the piston rod. If the space between abutment 32 and pin 25 is increased, the length of stroke of the piston rod will be decreased because abutmentless time elapses between the reversal of movement of the piston rod and the engagement by abutment 32 or pin 25 with its corresponding stempushing element.

The length of stroke in the form of the apparatus shown may be varied over a wide range in one particular form wherein the overall length of the apparatus as seen in FlGS. 2 and 3 is approximately twenty-six inches, the stroke length may be varied between one and six inches. in this typical installation, the speed range may 'be varied between zero and two hundred forty cycles per minute with a lifting capacity of one hundred pounds. The agitator may be employed for many purposes, such as clearing of parts from grease, paint and the like by shaking. By applying the modified form of end of the piston rod as seen in FIG. 6, the agitator may be employed to operate on both the push and pull strokes of the piston rod.

With respect to the piston rod, the latching yand releasing of the valve stem-pushing elements 40 and 41, it should be noted that by the novel arrangements shown, the valve-pushing elements are individually and alternately latched Iagainst inward movement toward and longitudinally of the valve stem until the other of the elements has been moved by one of the abutments on the piston rod in the same direction, but away from the valve stem to a predetermined position, whereupon the latching mechanism releases and allows the tension spring 42 to operate and thereby move the stem-pushing element which had ibeen previously latched to cause operation of the valve stem to change the air connections in the valve, and to simultaneously set up `another latching condition where the other stem-pushing element is latched against movement toward the valve stem. Once again, the latched stem-pushing element is prevented from moving longitudinally of the valve stem and toward the valve stem until the other element has moved in the same direction through a predetermined distance, whereupon the latching mechanism is released and the previously latched stem-pushing element operates to move the valve Stem and reverse the air connections in the valve.

It will be seen that l have provided an new and novel agitator apparatus wherein by simple means the movement of the piston rod is carefully controlled, lboth as t length of stroke as to speed of movement in both directions so as to adapt the agitator for a wide variety of uses w-herein the load m-ay be either suspended or may be actually both pushed or pulled during diiierent portions of the operating cycle.

It will, of course, be understood that various changes may be made in the form, detail, arrangement and proportion of the parts without departing from the scope of my invention which consists `of the matter described herein and set forth in the appended claims.

What is claimed is:

l. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder on the frame, and having air ports at opposite ends and also having a reciprocating piston and piston rod with a work-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, a two-position, :four-way air valve connected to said conduits and to said pipe and also having an `air exhaust port, said valve having a reciprocable operating stem extending generally parallel to the piston rod, said valve alternately and individually connecting said conduits to said pipe and to said exhaust port when said stem is longitudinally shifted in different directions, a pair of stem-pushing elements confronting the opposite ends of the stem for engaging the same, means mounting said elements for movement longitudinally of the stem, a tension spring interconnecting Said elements and maintaining at least one of said elements in engagement with the stem, latching means interconnecting said elements and alternately retaining each of said elements in a predetermined position against movement in one longitudinal direction until the other of said elements has moved a predetermined distance raw-ay lfrom the stem in the same longitudinal direction, a pair of spaced abutments on the piston rod and respectively positioned between said elements lfor alternately engaging and moving said elements through said predetermined distance as the rod is longitudinally moved in opposite directions, whereby to produce reciprocating movement of the rod and work-engaging media.

2. The invention set forth in claim l and including means adjustably mounting one of the abutments on the rod yfor movement therealong, whereby to facilitate changing of the length of stroke of the piston rod. i

3. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder on the frame and having air ports at opposite ends and yalso having a reciprocating piston and piston rod with -a work-engaging media thereon, la pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, a two-position four-way air valve connected to said conduits and to said pipe and also having yan air exhaust port, said valve having a reciprocable operating stem extending generally parallel to the piston rod, said valve -alternately and individually connecting said conduits to said pipe and to said exhaust port when said stem is longitudinally shifted in different direcftions, Ia pair of first and second stem-pushing elements having inner end portions respectively confronting the opposite ends of the stem for engagement therewith and also having outer portions spaced transversely from the stem, means pivotally mounting the outer portion of said rst element on the frame to permit swinging movement of the inner portion thereof in a direction longitudinally of the stem, mean-s mounting said second element to permit movement of the inner portion thereof longitudinally of the stern, a tension spring interconnecting the inner portions of said elements and maintaining at least one of said elements in engagement with the stem, latching means interconnecting said elements and -alternately retaining each of said elements in a predetermined position to prevent movement of the inner portion thereof toward the stem until the other of said elements has moved `a predetermined distance away from the stem in the same longitudinal direction, a pair of -abutments on the piston rod and respectively positioned between said elements for alternately engaging and lmoving the elements through said predetermined longitudinal distance as the rod is longitudinally moved in opposite directions, whereby to produce reciprocating movement of the rod and work-engagmg media.

4. A pneumatic reciprocating agitator, comprising an elongate trame, a pneumatic cylinder on the frame and having air ports at opposite ends and also having a reciprocating piston and piston rod with a work-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, a two-position four-way air valve connected to said conduits and to said pipe and also having an air exhaust port, said valve having a reciprocable operating stern extending generally parallel to the piston rod, the valve alternately and individually connecting said conduits to said pipe and to said exhaust port when the stem is longitudinally shifted in different directions, a pair of rst and second stem-pushing elements having inner portions respectively confronting opposite ends of the stem for engaging the same, said elements also having outer portions spaced transversely from the stem, a pivot on the frame swingably mounting the outer portion of said first element to permit swinging of the inner portion thereof in a direction longitudinally along the stem, a slide on the frame and mounting said second element, said swingable first element having a projection adjacent the outer portion thereof, said projection and the end of the slide extending in opposite directions and in juxtaposed and engaging relation with each other to prevent swinging of the inner portion of said iirst element toward said stem, the end of said projection being swingable into confronting and engaging relation with the end of the slide to prevent movement of said second element toward the stern, and a pair of spaced abutments on the piston rod and respectively positioned between said elements for alternately and individually moving one element to change the relationship of said slide and projection to permit the spring to move the other of said ele-ments, whereby to operate the valve with a snap action and to produce reciprocating movement of the rod and workengaging media.

5. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder n the frame and having air ports at opposite ends and also having a reciprocating piston and piston rod with a work-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, a two-position four-way air valve connected to said conduits and to said pipe and also having an air exhaust port, said valve having a reciprocable operating stem extending generally parallel to the piston rod, said valve alternately and individually connecting said conduits to said pipe and to said exhaust port when said stem is longitudinally shifted in diterent directions, a pair of stem-pushing elements confronting the opposite ends of the stem for engaging the same, means mounting said elements for movement longitudinally of the stern, a tension spring interconnecting said elements and maintaining at least one of the elements in engagement with the stem, latching means interconnecting said elements and alternately and individually preventing movement of each of said elements toward the stem until the other of said elements is moved a predetermined distance away from the stem, a pair of spaced abutments on the piston rod and respectively positioned between said elements for alternately engaging and moving said elements through a predetermined distance as the rod is longitudinally moved in opposite directions, a housing confining the cylinder, air valve, stem-pushing elements, latching means and abutments and having a slot therein extending parallel to the piston rod, a handle connected to one of the abutments and extending through said slot to the exterior of the housing, the handle cooperating with the corresponding abutment and gripping the rod, said handle and abutment having a threaded interconnection to permit loosening of the grip on therod to permit the abutment to be adjusted along the rod, whereby to change the length of stroke of the piston.

6. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder on the frame and having air ports at opposite ends and also having a reciprocating piston and piston rod with a lwork-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, a two-position four-way air valve connected to said conduits and to said pipe and also having an air exhaust pipe, said valve having a reciprocable operating stem extending gene-rally parallel to the piston rod, said valve alternately and individually connecting said conduits to said pipe and to said exhaust port when said stem is longitudinally shifted in different directions, a pair of stem-pushing elements confronting the opposite ends of the stem for engaging the same, means mounting said elements for movement .longitudinally ot the stem, a tension spring interconnecting said elements and maintaining at least one oftsaid elements in engaging relation with the stem, latching means interconnecting said elements and alternately and individually preventing each of said elements from moving toward the stern until the other of said elements is moved away from the stem in a longitudinal direction, one of said elements having a hole therethrough of'reduced size with respect to the stern, a reduced extension on the stern and slidably extending through said hole, a stop mounted on the frame and being shiftable into and out of confronting relation with the extension to prevent movement thereof and thereby prevent the valve from operating and thereby stop the reciprocating movement of the rod, and a pair of spaced abutments on the piston rod and respectively positioned between said elements for alternately engaging and moving said elements through said predetermined distance as the rod is longitudinally moved in opposite directions and thereby produce reciprocating movement of the rod and work-engaging media.

7. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder on the frame and having air ports at opposite ends and also having a reciprocating piston and piston rod with a Work-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, valve means for alternately and individually connecting said conduits in ilow communication with said pipe and with the atmosphere, and each of said conduits having a regulating valve therein for regulating flow of air, said regulating valve including a check valve permitting free air flow into and restricting air flow out of the cylinder and said regulating valve also including an adjustably variable continuous flow channel carrying the ow of air out of the cylinder at a desired rate, whereby to permit varying the speed of the piston in each direction.

8. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder on the frame and having air ports at opposite ends and also having a reciprocating piston and a piston rod with a work-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air under pressure, valve means for alternately and individually connecting each of said conduits in How-communication with said pipe and with the atmosphere, control mechanism on the frame and piston and connected with said valve means for 'operating the same, said control means including an abutnient adjustably mounted on the piston and causing the control mechanism and valve means to operate when the piston is in a predetermined position, and each of said conduits having a regulating valve therein for regulating flow of air, said regulating valve including a check valve permitting free air liow into and restricting air liow out of the cylinder, and said regulating valve also including an adjustably variable continuous ow channel carrying the flow out of the cylinder at a desired rate, whereby the air is controlled for producing the desired length of stroke and speed of `movement in both directions of the piston and work-engaging media.

9. A pneumatic reciprocating agitator, comprising an elongate frame, a pneumatic cylinder on the frame and having air ports at opposite ends and also having a reciprocating piston and piston rod with a work-engaging media thereon, a pair of air conduits each connected to a respective air port, an air supply pipe to be connected to a source of air Linder pressure, a two-position 4-way air valve connected to said conduits and to said pipe and also having an air exhaust port, said valve having a reciprocable operating stem extending generally parallel to the piston rod, the valve alternately and individually connecting said conduits to said pipe and to said exhaust port when the stem is iongitudinally shifted in different directions, a pair of irst and second sternpushing elements having inner portions respectively confronting opposite ends of the stern for engaging the same, said elements having outer portions spaced transversely from the stern, a pivot on the frame swingably mounting the outer portion of said first element to permit swinging of the inner portion thereof in a direction longitudinally along the stem, a slide on the frame and mounting said second element, said swingable irst element having a projection adjacent the outer portion thereof, said projection and the end of said slide extending in opposite directions and in juxtaposed and engaging relation with each other to prevent swinging of the inner portion of said iirst element toward said stem, the end of said projection being swingable into confronting and engaging relation with the end of the slide to prevent movement of said second element toward the stern, a pair of spaced abutments on the piston rod and respectively lpositioned between said elements for alternately and individually engaging and moving said elements to change the relationship of said slide and projection to permit the spring to move the other of said elements, a handle connected to one of the abutments and extending through said slot to the exterior of the housing, the handle cooperating with the corresponding abutment in gripping the rod, said handle and abutment having a threaded interconnection to perrnit loosening of the grip on the rod to permit the abutment to be adjusted along the rod, whereby to cause the valve to be operated with a snap action at varying positions of the piston rod so as to produce reciprocating movement of the rod and Work-engaging media and the controlled length of stroke.

References Cited in the tile of this patent UNITED STATES PATENTS 2,090,575 De Motte Aug. 17, 1937 2,286,026 Towler et al. June 9, 1942 2,453,844 Hungate Nov. 16, 1948 2,541,464 Davies Feb. 13, 1951 2,590,014 Ivanoi et al. Mar. 18, 1952 2,804,055 Hill et al Aug, 27, 1957 2,893,354 Austin et al. July 7, 1959 2,977,040 Dulebohn et al. Mar. 28, 1961 

1. A PNEUMATIC RECIPROCTING AGITATOR, COMPRISING AN ELONGATE FRAME, A PNEUMATIC CYLINDER ON THE FRAME, AND HAVING AIR PORTS AT OPPOSITE ENDS AND ALSO HAVING A RECIPROCATING PISTON AND PISTON ROD WITH A WORK-ENGAGING MEDIA THEREON, A PAIR OF AIR CONDUITS EACH CONNECTED TO A RESPECTIVE AIR PORT, AN AIR SUPPLY PIPE TO BE CONNECTED TO A SOURCE OF AIR UNDER PRESSURE, A TWO-POSITON, FOUR-WAY AIR VALVE CONNECTED TO SAID CONDUITS AND TO SAID PIPE AND ALSO HAVING AN AIR EXHAUST PORT, SAID VALVE HAVING A RECIPROCABLE OPERATING STEM EXTENDING GENERALLY PARALLEL TO THE PISTON ROD, SAID VALVE ALTERNATELY AND INDIVIDUALLY CONNECTING SAID CONDUITS TO SAID PIPE AND TO SAID EXHAUST PORT WHEN SAID STEM IS LONGITUDINALLY SHIFTED IN DIFFERENT DIRECTIONS, A PAIR OF STEM-PUSHING ELEMENTS CONFRONTING THE OPPOSITE ENDS OF THE STEM FOR ENGAGING THE SAME, MEANS MOUNTING SAID ELEMENTS FOR MOVEMENT LONGITUDINALLY OF THE STEM, A TENSION SPRING INTERCONNECTING SAID ELEMENTS AND MAINTAINING AT LEAST ONE OF SAID ELEMENTS IN ENGAGEMENT WITH THE STEM, LATCHING MEANS INTERCONNECTING SAID ELEMENTS AND ALTERNATELY RETAINING EACH OF SAID ELEMENTS IN A PREDETERMINED POSITION AGAINST MOVEMENT IN ONE LONGITUDINAL DIRECTION UNTIL THE OTHER OF SAID ELEMENTS HAS MOVED A PREDETERMINED DISTANCE AWAY FROM THE STEM IN THE SAME LONGITUDINAL DIRECTION, A PAIR OF SPACED ABUTMENTS ON THE PISTON ROD AND RESPECTIVELY POSITIONED BETWEEN SAID ELEMENTS FOR ALTERNATELY ENGAGING AND MOVING SAID ELEMENTS THROUGH SAID PREDETERMINED DISTANCE AS THE ROD IS LONGITUDINALLY MOVED IN OPPOSITE DIRECTIONS, WHEREBY TO PRODUCE RECIPROCATING MOVEMENT OF THE ROD AND WORK-ENGAGING MEDIA. 